Civil Engineering Reference
In-Depth Information
Table 1.1
Definition of landslide features
No. Name
Definition
1
Crown
Practically undisplaced material adjacent to highest parts of main scarp
2
Main scarp
Steep surface on undisturbed ground at upper edge of landslide caused by
movement of displaced material (13, stippled area) away from undisturbed
ground; it is visible part of surface rupture (10)
3
Top
Highest point of contact between displaced material (13) and main scarp (2)
4
Head
Upper parts of landslide along contact between displaced material and main
scarp (2)
5
Minor scarp
Steep surface on displaced material of landslide produced by differential
movements within displaced material
6
Main body
Part of displaced material of landslide that overlies surface of rupture between
main scarp (2) and toe of surface of rupture (11)
7
Foot
Portion of landslide that has moved beyond toe of surface of rupture (11) and
overlies original ground surface (20)
8
Tip
Point on toe (9) farthest from top (3) of landslide
9
Toe
Lower, usually curved margin of displaced material of a landslide, most distant
from main scarp (2)
10
Surface of rupture
Surface that forms (or that has formed) lower boundary of displaced material
(13) below original ground surface (20); mechanical idealization of surface of
rupture is called
sliding surface
in stability analysis
11
Toe of surface of
rupture
Intersection (usually buried) between lower part of surface of rupture (10) of a
landslide and original ground surface (20)
12
Surface of separation
Part of original ground surface (20) now overlain by foot (7) of landslide
13
Displaced material
Material displaced from its original position on slope by movement in landslide;
forms both depleted mass (17) and accumulation (18); it is stippled in Figure 1.6
14
Zone of depletion
Area of landslide within which displaced material (13) lies below original
ground surface (20)
15
Zone of
accumulation
Area of landslide within which displaced material lies above original ground
surface (20)
16
Depletion
Volume bounded by main scarp (2), depleted mass (17), and original ground
surface (20)
17
Depleted mass
Volume of displaced material that overlies surface of rupture (10) but underlies
original ground surface (20)
18
Accumulation
Volume of displaced material (13) that lies above original ground surface (20)
19
Flank
Undisplaced material adjacent to sides of surface of rupture; compass directions
are preferable in describing flanks, but if left and right are used, they refer to
flanks as viewed from crown
20
Original ground
surface
Surface of slope that existed before landslide took place
the shear strength of the rock (resisting force)
on this surface, then the slope will be unstable.
Instability could take the form of displacement
that may or may not be tolerable, or the slope
may collapse either suddenly or progressively.
The definition of instability will depend on the
application. For example, an open pit slope may
undergo several meters of displacement without
effecting operations, while a slope supporting a
bridge abutment would have little tolerance for
movement. Also, a single rock fall from a slope
above a highway may be of little consequence if
there is an adequate ditch to contain the fall, but
failure of a significant portion of the slope that
